【新文速递】2024年2月8日固体力学SCI期刊最新文章

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今日更新：International Journal of Solids and Structures 1 篇，Mechanics of Materials 1 篇，Thin-Walled Structures 1 篇

International Journal of Solids and Structures

Ultra-long-range force transmission in fiber networks enabled by multiaxial mechanical coupling

Jingnan Liu, Mengyuan Wang, Chao Xue, Hongfa Wang, Hailong Wang

doi:10.1016/j.ijsolstr.2024.112698

利用多轴机械耦合实现光纤网络中的超远距离力传输

Force transmission in the extracellular matrix is crucial for cellular mechanosensing. This transmission is influenced by factors such as tension–compression asymmetric stiffness and the fiber alignment of fibrous materials. However, the role of the anomalous Poisson’s ratio, intrinsic to fibrous materials, in force transmission remains underexplored. In this study, we utilize discrete fiber network simulations with different levels of connectivity to examine the stress decay of cell contraction in fibrous matrices. Our findings show that highly connected fiber networks exhibit reduced fiber alignment and atypical tensile hoop stress. This leads to an ultra-slow decay of radial stress induced by isotropic contraction of spherical cells. Delving deeper, we discovered that the increase of network connectivity corresponded to an enhanced Poisson’s ratio, signifying a pronounced multiaxial coupling effect. To fully comprehend this multiaxial coupling, we develop a constitutive law for fibrous materials. This law considers the stiffening along the tensile direction and their significant transverse contraction. Theoretical analysis elucidates that the stress decay of cell contraction adheres to a scaling law, represented as σrr-n, with the decay exponent n ranging from 1.5 to 3. Notably, this finding diverges from prior predictions that n is more than 2. The combination of a high tension-to-compression stiffness ratio with strong multiaxial coupling leads to ultra-long-range force transmission in fibrous materials. This ultra-long-range force transmission is marked by a convergent diminishing n approximating 1.5. In summary, our study provides a quantitative framework for elucidating the maximum limit of the force transmission range and serves as a guideline for developing innovative biomimetic materials.

细胞外基质中的力传递对于细胞机械传感至关重要。这种传递受到纤维材料的拉伸-压缩不对称刚度和纤维排列等因素的影响。然而，纤维材料固有的反常泊松比在力传递中的作用仍未得到充分探索。在本研究中，我们利用不同连通性水平的离散纤维网络模拟来研究纤维基质中细胞收缩的应力衰减。我们的研究结果表明，高度连通的纤维网络表现出纤维排列减少和非典型拉伸箍应力。这导致球形细胞各向同性收缩引起的径向应力超慢衰减。深入研究后，我们发现网络连通性的增加与泊松比的提高相对应，这表明存在明显的多轴耦合效应。为了充分理解这种多轴耦合，我们开发了纤维材料的构成定律。该定律考虑了纤维材料沿拉伸方向的刚度及其显著的横向收缩。理论分析表明，细胞收缩的应力衰减遵循σrr-n 的缩放定律，衰减指数 n 在 1.5 到 3 之间。高拉伸-压缩刚度比与强多轴耦合的结合导致了纤维材料中的超远距离力传递。这种超长距离力传递的特点是 n 趋近于 1.5 的收敛递减。总之，我们的研究为阐明力传递范围的最大极限提供了一个定量框架，可作为开发创新型仿生材料的指南。

Mechanics of Materials

An end-to-end explainable graph neural networks-based composition to mechanical properties prediction framework for bulk metallic glasses

Tao Long, Zhilin Long, Bo Pang

doi:10.1016/j.mechmat.2024.104945

基于可解释图神经网络的块状金属玻璃从成分到机械性能的端到端预测框架

Accurate prediction of the properties of bulk metallic glasses (BMGs) can provide an important guideline for the design of novel BMGs. While various machine learning (ML) models have been employed to predict the properties of BMGs, feature engineering is typically necessary to choose suitable descriptors based on domain knowledge or experience. In this work, an end-to-end generic framework has been proposed based on graph neural networks (GNNs) for composition-to-property prediction of BMGs. Firstly, an innovative graph representation of alloy compositions is designed. Then, two classes of GNNs have been developed to predict the fracture strength and plastic strain of BMGs. The R2 values for the optimal model on the test set were 0.963 and 0.801, respectively. Additionally, the optimal model has been fine-tuned using transfer learning for the problem of skewed distributions in the plastic strain dataset. As a result, the R2 scores on the test set improved significantly by 23.8% and 6.24%, respectively. Finally, a Hybrid Explainer has been developed to explain the entire prediction process of the model. The results of this study indicate that the proposed GNNs models may be informative for the rational design of BMGs.

准确预测块状金属玻璃（BMGs）的特性可为新型 BMGs 的设计提供重要指导。虽然各种机器学习（ML）模型已被用于预测块状金属玻璃的特性，但特征工程通常需要根据领域知识或经验选择合适的描述符。在这项工作中，我们提出了一个基于图神经网络（GNN）的端到端通用框架，用于从成分到属性预测 BMG。首先，设计了一种创新的合金成分图表示法。然后，开发了两类图神经网络来预测 BMG 的断裂强度和塑性应变。测试集上最优模型的 R2 值分别为 0.963 和 0.801。此外，针对塑性应变数据集中的偏斜分布问题，利用迁移学习对最优模型进行了微调。结果，测试集上的 R2 分数分别显著提高了 23.8% 和 6.24%。最后，还开发了一个混合解释器来解释模型的整个预测过程。本研究的结果表明，所提出的 GNNs 模型可能对合理设计 BMG 具有参考价值。

Thin-Walled Structures

Buckling and post buckling analysis of spatial thin film structures under shearing based on perturbation method

Meng Li, Bo-Hua Sun

doi:10.1016/j.tws.2024.111679

基于扰动法的剪切作用下空间薄膜结构的屈曲和后屈曲分析

Spatial thin film structures exhibit high sensitivity to shear deformation, often exhibiting wrinkling phenomena under minimal shear loads. In this study, we used a combined experimental and theoretical approach to investigate the wrinkling and post-buckling behaviors of thin films subjected to shear forces. Initially, we designed and fabricated a high-precision experimental apparatus, which, in conjunction with the MTS Exceed 40 series universal testing machine, was a versatile experimental platform for evaluating the responses of thin films to shear. Subsequently, we extended the classical Föppl–von Kármán nonlinear plate model to capture the large deformation behaviors of thin films under shear. This development led to the formulation of governing equations that describe the shear-induced deformation of the films. We introduced two boundary conditions to characterize these deformations: one in which the non-loaded edge was free (unconstrained), and another in which the non-loaded edge was constrained (analogous to a frame constraining a painting). To solve the governing equations, we treated the incremental shear displacement angle of the thin film as a small parameter and devised a numerical method grounded in perturbation theory. We further formulated an implicit difference method of arbitrary order accuracy to enhance the precision and stability of the numerical solution. Our experimental and theoretical analyses revealed a comprehensive buckling pathway for thin films under shear, characterized by an initial wrinkling configuration (Config. 1), followed by a transition to a secondary wrinkling state (Config. 2), and culminating in a wrinkling splitting pattern (Config. 3). We also determined that by increasing the pre-stretching of thin films, their resistance to wrinkling along the entire buckling pathway could be significantly enhanced.

空间薄膜结构对剪切变形具有高度敏感性，通常在最小剪切负荷下就会出现起皱现象。在本研究中，我们采用实验和理论相结合的方法来研究薄膜在剪切力作用下的起皱和后屈曲行为。首先，我们设计并制造了一台高精度实验仪器，该仪器与 MTS Exceed 40 系列万能试验机配合使用，是评估薄膜剪切响应的多功能实验平台。随后，我们扩展了经典的 Föppl-von Kármán 非线性板模型，以捕捉薄膜在剪切作用下的大变形行为。这一发展促成了描述薄膜剪切变形的控制方程的形成。我们引入了两种边界条件来描述这些变形：一种是非负载边缘是自由的（无约束），另一种是非负载边缘是受约束的（类似于画框对绘画的约束）。为了求解控制方程，我们将薄膜的增量剪切位移角视为一个小参数，并设计了一种基于扰动理论的数值方法。我们进一步制定了一种任意阶精度的隐式差分法，以提高数值求解的精度和稳定性。我们的实验和理论分析揭示了薄膜在剪切力作用下的综合屈曲途径，其特点是初始起皱构型（构型 1），随后过渡到二次起皱状态（构型 2），并最终形成起皱分裂模式（构型 3）。我们还确定，通过增加薄膜的预拉伸，可以显著增强薄膜在整个弯曲路径上的抗皱性。

来源：复合材料力学仿真Composites FEM

【新文速递】2024年2月12日复合材料SCI期刊最新文章

今日更新：Composite Structures 1 篇，Composites Part A: Applied Science and Manufacturing 1 篇，Composites Part B: Engineering 1 篇，Composites Science and Technology 1 篇Composite StructuresDamage monitoring of pinned hybrid composite-titanium joints using direct current electrical resistance measurementAndreas Dengg, Christoph Kralovec, Martin Schagerldoi:10.1016/j.compstruct.2024.117972利用直流电阻测量法监测插销式混合材料-钛接头的损坏情况The present research addresses structural health monitoring of pinned, composite-titanium (i.e.: hybrid) joints with the aim of using their lightweight potential and damage tolerance in future aircraft designs. Together with additively manufactured titanium pins, protruding into the carbon-fiber composite, a single-lap shear joint specimen is monitored with direct current electrical resistance measurements (DC ERM) across the overlap, without conductivity-enhancing additives (e.g., carbon nanotubes), but rather with the pins’ complex electrical network that forms with the carbon-fiber composite. For a proof-of-concept demonstration, a structural test with quasi-static, tension-tension loading and unloading is performed. Using digital image correlation, degradation of the joint is monitored. Results are validated by a 2-dimensional finite element model, considering multiple damage states. For DC ERM, a damage indicator is proposed to evaluate the joint’s structural condition. It is shown that typical damage for this joint type reported literature (i.e., cracks occurring at the overlap ends) could be reproduced and detected by the electrical property change across the overlap. Under the given laboratory conditions, the proposed DC ERM damage indicator clearly shows a non-reversible increase in resistance by 3.8% due to damage, starting at first damage initiation and also reflecting further damage growth. Thereby, the method’s capability for damage detection and monitoring is demonstrated.本研究涉及对复合材料-钛（即：混合材料）插销接头的结构健康监测，目的是在未来的飞机设计中利用其轻质潜力和损伤容限。在不使用导电性增强添加剂（如碳纳米管）的情况下，而是利用销钉与碳纤维复合材料形成的复杂电网络，通过跨重叠部分的直流电阻测量（DC ERM）对单圈剪切连接试样进行监测。在概念验证演示中，进行了准静态、拉伸-张力加载和卸载的结构测试。利用数字图像相关性，对接头的退化进行监测。结果通过二维有限元模型进行验证，并考虑了多种损坏状态。针对直流 ERM，提出了一种损伤指标来评估接头的结构状况。结果表明，文献报道的这种接头类型的典型损坏（即发生在重叠端部的裂缝）可以通过整个重叠部分的电特性变化来再现和检测。在给定的实验室条件下，所提出的直流 ERM 损坏指示器清楚地显示出，由于损坏，电阻会出现 3.8% 的不可逆增长，这种增长从最初的损坏开始，同时也反映出损坏的进一步增长。由此可见，该方法具有检测和监测损坏的能力。Composites Part A: Applied Science and ManufacturingOn the surface characteristics and removability of RB-SiC composite processed by nanosecond pulsed laserHong An, Yongfeng Qian, Lin Zhang, Zhiyu Zhang, Hu Huang, Jiwang Yandoi:10.1016/j.compositesa.2024.108082 纳秒脉冲激光加工的 RB-SiC 复合材料的表面特性和可移除性The inherent hard-brittle nature of RB-SiC composite poses significant challenges for efficient machining, hindering its application and promotion. Laser processing is a non-contact treatment technique that can effectively modify the mechanical properties of the material surface, thereby altering its removability. Accordingly, the change in surface characteristics of RB-SiC composite induced by nanosecond laser irradiation was investigated. It was found that laser irradiation could effectively soften the RB-SiC composite (with a maximum reduction in hardness by 40.7%), and the softening degree was strongly dependent on the laser parameters. The chemical composition analysis showed that the SiC content was decreased while the Si content was increased after laser irradiation, which was mainly responsible for the hardness reduction of RB-SiC composite. In addition, compared to the original RB-SiC composite, the laser-irradiated samples exhibited enhanced weight loss during the polishing process. This work gives a feasible route to improve the removability of RB-SiC composite.RB-SiC 复合材料固有的硬脆特性给高效加工带来了巨大挑战，阻碍了其应用和推广。激光加工是一种非接触式处理技术，可有效改变材料表面的机械特性，从而改变其可去除性。因此，我们研究了纳秒激光辐照诱导 RB-SiC 复合材料表面特性的变化。研究发现，激光辐照能有效软化 RB-SiC 复合材料（硬度最大降低 40.7%），且软化程度与激光参数密切相关。化学成分分析表明，激光辐照后 SiC 含量降低，而 Si 含量增加，这是导致 RB-SiC 复合材料硬度降低的主要原因。此外，与原始的 RB-SiC 复合材料相比，激光辐照后的样品在抛光过程中表现出更大的失重。这项工作为改善 RB-SiC 复合材料的可去除性提供了一条可行的途径。Composites Part B: EngineeringOptical wood with switchable solar transmittance for all-round thermal managementHe Gao, Ying Li, Yanjun Xie, Daxin Liang, Jian Li, Yonggui Wang, Zefang Xiao, Haigang Wang, Wentao Gan, Lorenzo Pattelli, Hongbo Xudoi:10.1016/j.compositesb.2024.111287可切换太阳能透过率的光学木，实现全方位热管理Technologies enabling passive daytime radiative cooling and daylight harvesting are highly relevant for energy-efficient buildings. Despite recent progress demonstrated with passively cooling polymer coatings, however, it remains challenging to combine also a passive heat gain mechanism into a single substrate for all-round thermal management. Herein, we developed an optical wood (OW) with switchable transmittance of solar irradiation enabled by the hierarchically porous structure, ultralow absorption in solar spectrum and high infrared absorption of cellulose nanofibers. After delignification, the OW shows a high solar reflectance (94.9%) in the visible and high broadband emissivity (0.93) in the infrared region (2.5–25 μm). Owing to the exceptional mass transport of its aligned cellulose nanofibers, OW can quickly switch to a new highly transparent state following phenylethanol impregnation. The solar transmittance of optical wood (OW-II state) can reach 68.4% from 250 to 2500 nm. The switchable OW exhibits efficient radiative cooling to 4.5 °C below ambient temperature in summer (cooling power 81.4 W m−2), and daylight heating to 5.6 °C above the temperature of natural wood in winter (heating power 229.5 W m−2), suggesting its promising role as a low-cost and sustainable solution to all-season thermal management applications.日间被动辐射冷却和日光采集技术与节能建筑息息相关。尽管最近在被动冷却聚合物涂层方面取得了进展，但要在单一基材中同时结合被动增热机制以实现全方位热管理，仍然具有挑战性。在此，我们开发了一种光学木材（OW），这种木材具有分层多孔结构、超低太阳光谱吸收率和纤维素纳米纤维的高红外吸收率，因此可切换太阳照射的透射率。经脱木质素处理后，OW 在可见光区显示出较高的太阳反射率（94.9%），在红外区（2.5-25 μm）显示出较高的宽带发射率（0.93）。由于其排列整齐的纤维素纳米纤维具有优异的质量传输性能，OW 可以在苯乙醇浸渍后迅速切换到新的高透明状态。从 250 纳米到 2500 纳米，光学木材（OW-II 状态）的太阳透过率可达 68.4%。这种可切换的光学木材在夏季能以低于环境温度 4.5 °C 的温度进行高效辐射制冷（制冷功率为 81.4 W m-2），在冬季能以高于天然木材温度 5.6 °C 的温度进行日光加热（加热功率为 229.5 W m-2）。Composites Science and TechnologyMechanism of gas barrier improvement of graphene/polypropylene nanocomposites for new-generation light-weight hydrogen storageMufeng Liu, Kailing Lin, Mingyu Zhou, Andrew Wallwork, Mark A. Bissett, Robert J. Young, Ian A. Kinlochdoi:10.1016/j.compscitech.2024.110483 用于新一代轻质储氢的石墨烯/聚丙烯纳米复合材料的气体阻隔性改进机理Hydrogen is a promising energy source for the low-carbon economy but light-weight materials with excellent gas barrier properties are needed for its transport and storage. Nanocomposites can deliver such properties, using two-dimensional materials to provide a barrier within the polymer matrix. Herein, we have investigated the optimal characteristics of graphene-based fillers for their use as a hydrogen barrier in a polymer matrix. We employed reduced graphene oxide (rGO) and graphene nanoplatelets (GNPs) that presented distinct filler morphologies and melt-mixed them separately into isotactic polypropylene (PP). A reliable characterisation approach was developed to evaluate the effective aspect ratio of 2D nanomaterials within a polymer matrix by combining BET surface area for the effective thickness and microscopic measurement for lateral size on the microstructure of the nanocomposite samples. The effective aspect ratio values were evaluated to be 153 ± 85 for the rGO and 14 ± 6 the GNPs. Therefore, the rGO outperformed the GNPs in improving both the mechanical and H2 barrier properties of their nanocomposites. The modulus of PP was increased from 1.2 GPa to 2.3 GPa by the addition of 0.9 vol% of the rGO, whereas GNP-filled PP only reached 1.8 GPa by the addition of a higher loading of the GNP (4.6 vol%). The H2 permeability of PP-rGO nanocomposites compared to pure PP was reduced by 40% at 0.9 vol% loading, compared to PP-GNP samples which had a 30% reduction at 4.6 vol% loading. Nielson's model was employed to analyse the results, showing an effective aspect ratio of rGO and GNP to be 165 and 20 respectively, consistent with the characterisation results.氢是低碳经济中一种前景广阔的能源，但其运输和储存需要具有优异气体阻隔性能的轻质材料。纳米复合材料可以利用二维材料在聚合物基体中提供阻隔性，从而实现这种性能。在此，我们研究了石墨烯基填料在聚合物基体中用作氢气屏障的最佳特性。我们采用了还原氧化石墨烯 (rGO) 和石墨烯纳米片 (GNP)，它们呈现出不同的填料形态，并将它们分别熔融混合到异方性聚丙烯 (PP) 中。我们开发了一种可靠的表征方法，通过结合 BET 表面积（有效厚度）和显微镜测量（纳米复合材料样品微观结构的横向尺寸）来评估聚合物基质中二维纳米材料的有效长宽比。经评估，rGO 的有效长宽比值为 153 ± 85，GNPs 为 14 ± 6。因此，在改善纳米复合材料的机械性能和 H2 阻隔性能方面，rGO 优于 GNPs。添加 0.9 Vol% 的 rGO 后，聚丙烯的模量从 1.2 GPa 提高到 2.3 GPa，而添加更多 GNP（4.6 Vol%）后，填充 GNP 的聚丙烯的模量仅达到 1.8 GPa。与纯 PP 相比，PP-rGO 纳米复合材料的 H2 渗透率在 0.9 Vol% 的添加量下降低了 40%，而 PP-GNP 样品在 4.6 Vol% 的添加量下降低了 30%。采用尼尔森模型分析结果显示，rGO 和 GNP 的有效长宽比分别为 165 和 20，与表征结果一致。来源：复合材料力学仿真Composites FEM